[Bug libstdc++/91910] Debug mode: there is a racing condition between destructors of iterator and the associated container.

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91910

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Author: redi
Date: Fri Sep 27 16:20:40 2019
New Revision: 276184

URL: https://gcc.gnu.org/viewcvs?rev=276184&root=gcc&view=rev
Log:
PR libstdc++/91910 fix data race in Debug Mode destructors

Fix data race when _Safe_iterator_base::_M_detach() runs concurrently with
the _Safe_container_base destructor.

        PR libstdc++/91910
        * src/c++11/debug.cc (_Safe_iterator_base::_M_detach()): Load pointer
        atomically and lock the mutex before accessing the sequence.
        (_Safe_local_iterator_base::_M_detach()): Likewise.
        (_Safe_iterator_base::_M_reset()): Clear _M_sequence atomically.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/src/c++11/debug.cc